The present invention pertains to field emission displays and, more particularly, to a method of fabricating spacers for field emission displays.
It is known in the art to make spacer structures for use in field emission displays for the purpose of maintaining the separation between the cathode and the anode plates. Spacer materials commonly used are insulating in nature so that anode electrical potential is held off of the cathode plate. Failure of a spacer, typically in the form of a violent electrical discharge/arcing, results in catastrophic damage to the display. One known mechanism, which can result in such failure, is a reduction of component elements in the spacer material leading to a change in the insulative properties of the spacer material. For example, titanate based material systems are susceptible to reduction in the Tixe2x80x94O bond due to electron bombardment which can lead to Ti rich, conductive regions on the spacer surface. Once these regions form, conduction paths become present and arcing can occur causing display failure.
Several prior art spacers attempt to solve the problems of spacer breakdown and associated arcing. For example, it is known in the art to provide a spacer having a resistive coating. The resistive coating is applied over the bulk spacer material to prevent spacer material breakdown due to electron bombardment and to remove impinging electrons by conduction. However, these coatings are susceptible to mechanical damage and/or alteration, such as may occur during handling of the spacers. They are also susceptible to chemical alteration, which may change their resistivity. Another disadvantage to coated spacers is a thermal expansion mismatch between bulk spacer material and spacer coating which can cause interfacial stresses between the bulk spacer material and spacer coating. This can lead to cracks in the coating and spacer breakdown. Spacer coating methods employ additional processing steps in the fabrication of a field emission display which, adds time, complexity and cost to the process. In addition, maintaining coating thickness during fabrication is problematic due the complex coating process and additional handling of spacers after the coating process.
Accordingly, there exists a need for a method of fabricating a field emission display having passivated spacers which eliminates the need for a spacer coating, prevents spacer breakdown due to electron bombardment and is simple and cost effective.